Fuel module

ABSTRACT

The invention relates to a fuel module for the introduction of fuel from a fuel tank  91 ) to an internal combustion engine, comprising a supply pump ( 9 ), through which fuel is taken up and supplied to a container ( 2 ) and a main pump ( 3 ), which takes up fuel from the container ( 2 ) and supplies the internal combustion engine at high pressure. The supply pump ( 9 ) is a low-pressure pump, the outlet of which feeds into the container ( 2 ) through a fine filter ( 11 ).

BACKGROUND OF THE INVENTION

[0001] The invention is concerned with a fuel module for supplying fuelfrom a fuel tank to an internal combustion engine, having a feed pumpwhich is used to take up fuel and feed it into a container, and having amain pump which takes up fuel from the container and supplies it at highpressure to the internal combustion engine, the feed pump being a pumpwhich feeds at a low pressure and the pump outlet of which leads intothe container via a fine filter.

[0002] In fuel modules of this type, it is known to arrange a finefilter in the line leading from the outlet of the main pump to theinternal combustion engine. Although coarse filters are also frequentlyarranged on the main pump intake duct, these can only filter outparticles from the fuel which are larger than approximately 40 to 100μm. Smaller particles pass through the main pump and are filtered outonly in the fine filter. This leads to problems if the moveablecomponents of the main pump are arranged in the fixed components withonly a small amount of play, so that gaps of the order of magnitude ofonly 10 to 20 μm are present between these components. These small gapsmay become clogged up or damaged by the dirt particles which have passedthrough the coarse filter, with the result that the functioning of themain pump is impaired.

[0003] The replacement of the coarse filter on the main pump intake ductby a fine filter could be undertaken only with very large filterelements, since the soiling capacity which is possible over the lifetimeof a motor vehicle would have to be in the region of several grams inorder to ensure that the filter still allows a sufficient amount of flowto pass through it.

[0004] Since the suction action of the main pump is relatively small andlies in the region of only a few millibars, even with little soiling ofthe filter this suction action is no longer sufficient in order to takefuel into the pump to a sufficient extent, and so evaporation of thefuel in the fine filter occurs and thereby results in the pump havinghot feeding problems which interfere with the functioning of the pump oreven render it completely incapable of functioning.

[0005] DE-A-44 25 670 discloses a fuel module of the type mentioned atthe beginning.

[0006] US-A-47 70 150 discloses a fuel module for supplying fuel from afuel tank to an internal combustion engine, the module having a feedpump which is used to take up fuel. The fuel is fed by the feed pump viaa heat exchanger, a main filter and a fine filter to the injection pumpof the internal combustion engine.

[0007] DE-A-198 46 616 discloses a fuel module for feeding fuel from afuel tank to an internal combustion engine, the module having a feedpump which takes up fuel via a first filter and feeds it into acontainer. Fuel is taken up from the container via a fine filter by amain pump and supplied to the internal combustion engine.

[0008] It is the object of the invention to provide a fuel module of thetype mentioned at the beginning which enables the use of main pumps ofsmall dimensions, the functioning of which is ensured over theirlifetime and in which there is no drop over the lifetime in the feedquantity of the fuel supplied to the internal combustion engine.

[0009] This object is achieved according to the invention by the factthat the container is a closed container in which the main pump isarranged.

BRIEF DESCRIPTION OF THE INVENTION

[0010] The feed pump is used to feed large circulating quantities offuel through the fine filter at relatively low pressures. The feed pumppressure acting on the fine filter is much larger than a possiblenegative suction pressure which can be produced by the feed pump, so theflow passes without any problem through the fine filter. Evaporations ofthe fuel in the fine filter do not lead to hot feeding problems in themain pump. The fuel which has already been finely filtered makes itpossible to use a main pump, which is designed as a flow pump and hassmall gap sizes between the moveable and fixed parts, the main pumpproducing the required high pressure in spite of its small size andbeing protected against wear by dirt particles.

[0011] There is no drop in pressure through a fine filter arrangeddownstream of the main pump in the direction of flow, and so thepressure produced by the main pump is also fully maintained to feed thefuel on further.

[0012] The closed container prevents, when the fuel tank is at leastlargely filled, unfiltered fuel from being able to pass into thecontainer and impair the functioning of the main pump.

[0013] In order to simplify the assembly, the main pump is arranged inthe container.

[0014] Since the feed pump does not have to produce any high pressures,it can be designed as a flow pump having relatively large gap sizesbetween the moveable and fixed parts, which means that the dirtparticles contained in the fuel do not impair the full functioningcapability of the feed pump.

[0015] In this case, the feed pump can produce a feed pressure ofapproximately 400 mbar to approximately 600 mbar, 10 preferably ofapproximately 500 mbar.

[0016] If the feed pump takes up fuel via a filter, it is alsoadequately protected against the wear by dirt particles.

[0017] In order to ensure a sufficient quantity of fuel at the feedpump, the feed pump can take up fuel from a feed pump container intowhich fuel is fed from the fuel tank by one or more suction jet pumps.

[0018] If a branch flow of the feed flow is supplied here from the pumpoutlet of the feed pump to the suction jet pump or suction jet pumps asoperating flow, then the main pump can be dimensioned exclusively forthe quantity of fuel which is to be fed to the internal combustionengine. In this case, the branch flow can be branched off from the feedflow both upstream and downstream of the fine filter. The advantage ofit branching off upstream of the fine filter is that the suction jetpump is more powerful.

[0019] So that a sufficient pressure is built up by the feed pump inorder to be able to operate the suction jet pump reliably, a restrictoragainst the resistance of which the feed pump has to feed can bearranged in the pump outlet of the feed pump, said outlet leading to thecontainer, the restrictor preferably being arranged downstream of thefine filter in the direction of flow in the pump outlet. The pressure atthe feed pump is then further increased and results in a furtherimprovement in the feeding activity of the suction jet pump if thethroughflow resistance of the fine filter is increased over the courseof its lifetime by the dirt particles which have been filtered out.

[0020] A construction which can be preassembled in a simple mannerresults if the feed pump is arranged in the feed pump container.

[0021] A pressure regulator which is used to determine the maximumpressure supplied to the internal combustion engine can be arranged inthe feed line leading from the main pump to the internal combustionengine.

[0022] If the cut-off line of the pressure regulator is guided here intothe feed pump container, it does not have to be fed once again from thesuction jet pump into the feed pump container, and the necessary powerof the suction jet pump can be restricted to the use of the internalcombustion engine.

[0023] If the main pump takes up fuel from the container via a furtherfilter, then residual dirt which is also still possible is kept awayfrom the main pump by this filter.

[0024] Likewise to simplify assembly, the main pump can be arranged inthe container.

BRIEF DESCRIPTION OF THE DRAWING

[0025] An exemplary embodiment of the invention is illustrated in thedrawing and will be described in greater detail below. The single figureof the drawing shows a diagrammatic construction of a fuel module whichis installed in a fuel tank.

[0026] The fuel tank 1 is a “saddle tank”, the two tank regions of whichare connected to each other. Arranged in a closed container 2 in theright-hand tank region is a main pump 3 which is designed as a flowpump, takes up fuel from the container 2 via a filter 4 of smallfiltering force and feeds it via a feed line 5 at high pressure to aninternal combustion engine (not illustrated).

[0027] A pressure regulator 6 which is fastened to a closure 21 of thetank opening 22 in the upper wall 15 of the fuel tank 1 is arranged inthe feed line 5 and its cut-off line 7 is guided into an upwardly openfeed pump container 8 which is arranged in the left-hand tank region.

[0028] The feed pump 9 is arranged in the feed pump container 8, thefeed pump being designed as a flow pump, taking up fuel from the feedpump container 8 via a filter 10 of small filtering force and pumping itat a feed pressure of approximately 500 mbar in a supply line 12 to thecontainer 2. A fine filter 11 is first of all arranged in the supplyline 12 in the feeding direction, said fine filter being situated on aclosure 13 of a tank opening 14 in the upper wall 15 of the fuel tank 1.In the direction of flow downstream of the fine filter 11, a restrictor16 is arranged in the supply line 12 at the point at which it opens intothe container 2, the restrictor ensuring that a certain pressure isbuilt up in the supply line 12 by the feed pump 9.

[0029] Two branch lines 17, 17′ lead off from the supply line 12upstream of the fine filter 11 and are used to guide branch flows of thefeed flow of the feed pump 9 to suction jet pumps 18, 18′ and to drivethe latter. The suction jet pumps 18, 18′ take up fuel from the fueltank 1 via suction openings 19, 19′ and feed it together with the fuelof the branch flows of the feed flow of the feed pump 9 into the feedpump container 8 directly (suction jet pump 18) or via a feed line 20(suction jet pump 18′).

1. A fuel module for supplying fuel from a fuel tank to an internalcombustion engine, having a feed pump which is used to take up fuel andfeed it into a container, and having a main pump which takes up fuelfrom the container and supplies it at high pressure to the internalcombustion engine, the feed pump being a pump which feeds at a lowpressure and the pump outlet of which leads into the container via afine filter, characterized in that the container is a closed container(2) in which the main pump (1) is arranged.
 2. The fuel module asclaimed in claim 1, characterized in that the feed pump (9) is a flowpump.
 3. The fuel module as claimed in one of the preceding claims,characterized in that the feed pump (9) produces a feed pressure ofapproximately 400 mbar to approximately 600 mbar.
 4. The fuel module asclaimed in claim 3, characterized in that the feed pump (9) produces afeed pressure of approximately 500 mbar.
 5. The fuel module as claimedin one of the preceding claims, characterized in that the feed pump (9)takes up fuel via a filter (10).
 6. The fuel module as claimed in one ofthe preceding claims, characterized in that the feed pump (9) takes upfuel from a feed pump container (8) into which fuel is fed from the fueltank (1) by one or more suction jet pumps (18, 18′).
 7. The fuel moduleas claimed in claim 6, characterized in that a branch flow of the feedflow is supplied from the pump outlet of the feed pump (9) to thesuction jet pump or suction jet pumps (18, 18′) as operating flow. 8.The fuel module as claimed in claim 7, characterized in that arestrictor (16) is arranged in the pump outlet of the feed pump (9),said outlet leading to the container (2).
 9. The fuel module as claimedin claim 8, characterized in that the restrictor (16) is arrangeddownstream of the fine filter (11) in the direction of flow in the pumpoutlet.
 10. The fuel module as claimed in one of the preceding claims,characterized in that the feed pump (9) is arranged in the feed pumpcontainer (8).
 11. The fuel module as claimed in one of the precedingclaims, characterized in that a pressure regulator (6) is arranged inthe feed line (5) leading from the main pump (1) to the internalcombustion engine.
 12. The fuel module as claimed in claim 11,characterized in that the cut-off line (7) of the pressure regulator (6)is guided into the feed pump container (8).
 13. The fuel module asclaimed in one of the preceding claims, characterized in that the mainpump (1) takes up fuel from the container (2) via a filter (4).